FAMILY ACERID^ — BULLA. 17 



Bulla triticea. 



PLATE XXXV. FIG. 326. 



Bulla triticea. CouTHOOY, Bost. Jour. Nat. Hist. Vol. 2, p. 88, pi. 1, fig. 8. 

 B. id. RussEL, Essex Jour. Nat. Hist. Vol. 1, p. 75. 

 B. id. Gould, Invertebrata of Mass. p. 1G5, fig. 98. 



Description. Shell polished, cylindrical, rather solid. Spire slightly depressed, imper- 

 forate. Surface traversed longitudinally and transversely by numerous microscopic strife. 

 Lip inserted into, or rather arising from, the margin of the circular pit at the summit of the 

 spire. Aperture narrowr above, almost linear, except at the base, where it is dilated to double 

 its previous breadth by the sudden curvature of the columella, which is slightly reflected upon 

 the body of the shell. At the region of the umbilicus is a flattened white space, thickened 

 by enamel, gradually disappearing within the aperture. The whole inner margin is some- 

 times slightly coated with enamel. 



Color. Dull white, covered with a thin shining ferruginous epidermis. Columella white. 



Length, 0'3; diameter, 0"1. 



Neither this shell nor the preceding has been yet found in situ. The present species has 

 only been obtained from the maws of fishes on the coast of Massachusetts, but will probably 

 be found here. 



Bulla debills. 



PLATE XXXy. FIG. 329. 



Bulla debilis. GoDLD, Am. Jour. Sc. Vol.38, p. 196. 

 Bulla drbtlis. Id. Invertebrata of IVlass. p. 164, fig. 95. 



Description. Shell small, obliquely ovate, tumid, thin and brittle. Whorls four, all rising 

 to about the same height ; divisions distinct, each very convexly rounded. Last whorl the 

 whole length of the shell, including all the others, and partially detached from them above. 

 Surface smooth, without any apparent mark. Aperture as long as the shell, widening from 

 above. Outer lip attached behind, a little before the summit of the shell, rising to a 

 level with the spire, then descending in a regular though slightly waved curve to the front 

 of the pillar, where it terminates abruptly. Inner lip spread out into a thin enamel upon the 

 body of the shell, partially covering an umbilical indentation placed at about one-fourth the 

 length of the shell. 



Color. Greenish white. 



Length, 0"I; diameter, 0"13. 



According to its original describer, this shell has as yet no determinate locality, being 

 obtained only from the maws of fish in Massachusetts bay. The same writer suspects that 

 it may possibly be the young of B. gouldi, and that it bears a striking resemblance to the 



Fauna — Part 6. 3 



